Radio frequency selection and oscillatory amplification element



Patented May 16, 1939 UNITED STATES PATENT OFFICE RADIO FREQUENCYSELECTION AND OSCIL- LATORY AMPLIFICATION ELEMENT 2 Claims.

My invention relates generally to the use of an independent circuitelement consisting of a calibrated length of wire, wound or folded sothat there will not be any effective self inductance in the wire as awhole. The object of this invention is to show various communicationsystems and units which employ this circuit element.

The noninductive length of wire elements described as this invention areintended to be used when practicable in place of the conventionalcapacity-inductance tuned circuits which are now generally utilized forfrequency selection and oscillatory amplification means.

My length of wire element is composed of an electrical conductor woundor folded so that the electrostatic and electromagnetic fields createdby the resonant frequency current in one portion of the element areeffectively opposed and cancelled by the fields created by the currentin another portion of the element. In practical construction the lengthof wire element is composed of a group of substantially parallel wires,lying in the same general plane, and connected in series to form asubstantially noninductive conductor which can oscillate at the workingfrequency when it is properly connected to the resonate frequency power.

When the length of wire element circuit is terminated at each end by aseries resonant force-such as the plate and cathode terminals on anassociated radio tube-the electrical length in the circuit including thelength of wire element should be equal to a one half wavelength, or amultiple thereof, of the working frequency. The voltage potential is ata maximum difference between electrical midpoints, or half wavelengthpoints, in the element circuit.

The self inductance of the element is minimized by construction as thepresence of self inductance in the element will introduce to the elementcircuit the loss factor that is always associated with nonresonateinductance. Series condensers do not affect the operativeness of theelement circuit, and so may be used as desired.

In the drawing:

Figure 1 shows the length of wire element being employed as thefrequency selection and oscillatory amplification means in a singlefrequency receiving system.

Figure 2 shows the length of wire element utilized in the intermediatefrequency selection and oscillatory amplification circuit in aconventional superheterodyne receiving system.

Figure 3 shows the length of wire element utilized as the frequencydetermination means in a master oscillator circuit.

Figure 4 shows three length of wire elements, the selection beingaccomplished by a conventional receiver gang switch. This figureindicates the intention of this invention that a multiple number ofdifferent frequency length of wire elements may be employed in areceiving system so as to provide for multiple frequency reception.Conventional shielding of the length of wire elements may be employed.

Figure 5 indicates what is meant by a fanned output connection to alength of wire element.

Referring to the drawing the numeral 20 indicates a receiving antenna.2| indicates conventional antenna circuits. 22 is a length of wireelement which is operating in a full wavelength circuit. Only all phasevalues of one cycle of the working frequency are included in a fullwavelength circuit. The output conductor 23 is located at the electricalmid-point, or half wavelength point, in the element circuit. Item 24 isthe first amplifier tube. 25 is a second length of wire element which issimilar to the first length of wire element item 22.

Numeral 26 indicates the conventional antenna and selector circuits in asuperheterodyne receiving system. The beat frequency oscillator currentbeats against the incoming signal to form the intermediate frequencysignal. full wavelength length of wire element in a circuit operating onthe receiver intermediate frequency. 28 indicates the optimum widthoutput connection to the length of wire element, at the electricalmid-point of the element circuit.

Numeral 29 shows a half wavelength of wire element which serves as thefrequency determination means for the master oscillator circuit. Theelectrical midpoint, or half wavelength point, in this element circuitis located at the i extreme end of the element circuit. Item 3|]indicates a conventional capacity-inductance tuned circuit which may beutilized in this master oscillator circuit. 3| is a variable RF powertap to a noninductive length-of-wire item 32. erly varying the RF powertap on the noninductive length-of-wire the radiating antenna may be madethe exact desired electrical length.

Items 34a, 34b, and 340 are different operating frequency length of wireelements. The selection of any element and its associated outputconductor may be accomplished by the gang switches 35a and 35b.

Item 31 is an optimum width output conductor connected to the length ofwire element item 36.

Item 21 is a y P P- spond to a more or less wide band of frequencies.

There are several methods whereby the lengthof-wire circuit element maybe constructed so as to form a compact element. It is only necessarythat the fields of one length of wire be in the opposite direction tothe fields of one of the wires adjacent to it. Occasionally the purposesof this invention can be served by employing a straight length of wirein place of the folded wire. This would generally be possible on onlythe highest frequencies inasmuch as the length of the wire would beprohibitive on the lower frequencies.

Although I have shown and described herein preferred embodiments of myinvention, it is to be definitely understood that I do not desire tolimit application of the invention thereto, and any change or changesmay be made in the structure and arrangement of the parts within thespirit of the invention and scope of the subjoined claims.

What is claimed is:

1. A radio frequency selection element, including in combination, agroup of substantially parallel wires connected in series forming asubstantially noninductive conductor that can oscillate at the workingfrequency, and an output conductor connected to the noninductiveconductor at the electrical middlepoint of the latter.

2. A radio frequency selection element, including in combination, agroup of substantially parallel wires connected in series forming asubstantially noninductive conductor that can oscillate at the workingfrequency, and an output conductor connected to the noninductiveconductor with a fanned connection of optimum width.

WARREN C. HILL.

